I happened to mention to my brother that I would like to get an airbrush to play around with on some cakes. He said that he has a very good one just sitting around that he no longer uses and I can have it if I want it.

Is that even possible? I don't know anything about the mechanics of airbrushes so I don't know if it's possible to clean it well enough to ensure that there are no remnants of paint or past cleaning chemicals.

What do you think?

Not sure,maybe if you got it professional refurbished or cleaned?
Maybe you can just use the compressor and get new hoses and nozzle?
Sorry I can't be more help.

Personally, I would say yes, If your brother took really good care of it and cleaned it well then you're ahead of the eight ball.

If he didn't, then
This means you will need to take it apart and see if there is any residual paint from before. You need to look at every nook and cranny. And before you take it apart and decide you need to cuss me out, putting the brush back together is a royal PITA. Just a friendly warning.

The instructions for cleaning my airbrush is to use only distilled water for rinsing. Cleaning with air pressure and without is 1:1 isopropyl alcohol to distilled water. They emphasize distilled water. Then they say spray 2 to 3 airbrush cups through with the distilled water.

Spoony G has suggested to me to only clean with Vodka. I use an airbrush cleaner sold at my local cake supply store. It's by Bakery Crafts, AB-7071. The ingredients are listed as follows: water, anionic & nonionic surfactants, isopropyl alcohol, sodium citrate, sodium boride, sodium hydroxide. Use one full airbrush cup, then 2 to 3 airbrush cups of water. You are spraying all this stuff out.
Other things suggested by my manufacture was to get the plastic brush dental flossing things. Very specific about not using the ones with metal as the core.
The other thing they emphasized is clean it well after each use so you don't have to take it apart, because that's not good for the brush either.

I'm jealous, my brother always comes to my house to see what tools he can get from me.

Personally I wouldn't. But that is just me.

You can use the compressor and the hose, but I would buy a new airbrush gun that hasn't been used with anything.